chore: preserve google-cloud-spanner change

Until #17373 is
resolved, we have to keep the google-cloud-spanner manual fix.

Author: suztomo

packages/google-cloud-spanner/noxfile.py

@@ -43,6 +43,7 @@
     "pytest",
     "pytest-cov",
     "pytest-asyncio",
+    "pytest-xdist",
 ]
 MOCK_SERVER_ADDITIONAL_DEPENDENCIES = [
     "google-cloud-testutils",
@@ -240,6 +241,8 @@ def unit(session, protobuf_implementation):
     # Run py.test against the unit tests.
     args = [
         "py.test",
+        "-n",
+        "auto",
         "-s",
         f"--junitxml=unit_{session.python}_sponge_log.xml",
         "--cov=google",
@@ -754,7 +757,6 @@ def prerelease_deps(session, protobuf_implementation, database_dialect):
 def mypy(session):
     """Run the type checker."""
     session.skip("Mypy is not yet supported")
-
     # TODO(https://github.com/googleapis/gapic-generator-python/issues/2579):
     # use the latest version of mypy
     session.install(
@@ -832,12 +834,15 @@ def core_deps_from_source(session, protobuf_implementation):
     dep_paths = [str(deps_dir / dep) for dep in core_dependencies_from_source]
 
     session.install(*dep_paths, "--no-deps", "--ignore-installed")
+    session.install("pytest-xdist")
     print(
         f"Installed {', '.join(core_dependencies_from_source)} locally from {deps_dir}"
     )
 
     session.run(
         "py.test",
+        "-n",
+        "auto",
         "tests/unit",
         env={
             "PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION": protobuf_implementation,

packages/google-cloud-spanner/setup.py

@@ -60,7 +60,17 @@
     "google-cloud-monitoring >= 2.16.0",
     "mmh3 >= 4.1.0",
 ]
-extras = {"libcst": "libcst >= 0.2.5"}
+extras = {
+    "libcst": "libcst >= 0.2.5",
+    "test": [
+        "pytest",
+        "mock",
+        "asyncmock",
+        "pytest-cov",
+        "pytest-asyncio",
+        "pytest-xdist",
+    ],
+}
 
 url = "https://github.com/googleapis/google-cloud-python/tree/main/packages/google-cloud-spanner"